Co‐ingesting whey protein with dual‐source carbohydrate enhances amino acid availability without compromising post‐exercise liver glycogen resynthesis

Hannon, Sophie C ORCID: https://orcid.org/0000-0001-5835-0271, McStravick, James ORCID: https://orcid.org/0000-0001-6067-9893, Henthorn, Libby, Bawden, Stephen J ORCID: https://orcid.org/0000-0002-5157-3269, Tang, Jonathan CY ORCID: https://orcid.org/0000-0001-6305-6333, Dunn, Rachel, Makino, Ryosuke ORCID: https://orcid.org/0000-0001-7549-2159, Smith, Kenneth ORCID: https://orcid.org/0000-0001-8971-6635, Gonzalez, Javier T, Hodson, Nathan ORCID: https://orcid.org/0000-0003-1330-4030, Morton, James P ORCID: https://orcid.org/0000-0003-2776-2542, Kennerley, Aneurin J ORCID: https://orcid.org/0000-0002-7599-7461 and Hearris, Mark A ORCID: https://orcid.org/0000-0003-4909-6755 (2025) Co‐ingesting whey protein with dual‐source carbohydrate enhances amino acid availability without compromising post‐exercise liver glycogen resynthesis. The Journal of Physiology. JP288473. ISSN 0022-3751

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Abstract

We examined the effects of ingesting maltodextrin and/or fructose with protein co-ingestion on post-exercise liver and muscle glycogen resynthesis. Following glycogen-depleting exercise, 10 well-trained male cyclists ingested 60 g h−1 carbohydrate from either maltodextrin (MAL), fructose (FRU), 1:1 ratio of maltodextrin + fructose (MF) or 1:1 ratio of maltodextrin + fructose plus 30 g whey protein at 0 and 180 min (PRO) during a 5 h recovery period. 13C magnetic resonance spectroscopy and imaging were performed at 0, 120 and 300 min following exercise to determine liver and muscle glycogen concentrations and liver volume. Protein co-ingestion resulted in elevated serum insulin and plasma glucagon compared with FRU and MF (P < 0.001 for all). Similarly, serum insulin and plasma glucagon concentrations were markedly higher with MAL when compared with both FRU and MF (P < 0.05 for all), although plasma glucagon was also higher when compared with PRO (P < 0.001). Liver glycogen concentrations were significantly higher with FRU (275 ± 49 mmol L−1), MF (255 ± 50 mmol L−1) and PRO (283 ± 50 mmol L−1) compared with MAL (204 ± 51 mmol L−1) (P < 0.05 for all) following 5 h of recovery. However, muscle glycogen concentrations (mmol L−1: MAL, 168 ± 33; FRU, 145 ± 32; MF, 151 ± 33; PRO 153 ± 33) were not different between trials (P > 0.05). We conclude that, despite enhancing glucagonaemia, co-ingestion of whey protein (to a 1:1 combination of maltodextrin and fructose) does not compromise post-exercise liver glycogen resynthesis, allowing for increased aminoacidaemia alongside rapid glycogen resynthesis.